<PAGE>

                                                                 EXHIBIT 10.43

                                    AGREEMENT

         WHEREAS, CUseeMe Networks, Inc., a Delaware corporation (the
"Company") and David Bundy (the "Executive") are parties to that certain
Executive Retention Agreement, dated as of December 1, 2000 (the "Executive
Retention Agreement") and that certain Nondisclosure and Noncompetition
Agreement, dated February 15, 1996 (the "Offer Letter");

         WHEREAS, the Company is a party to that certain Agreement and Plan
of Merger and Reorganization, dated as of March 22, 2001 (the "Merger
Agreement"), between the Company, First Virtual Communications, Inc., a
Delaware corporation ("FVC"), and FVC Acquisition Corp., a Delaware
corporation and a wholly owned subsidiary of FVC;

         WHEREAS, as an inducement to FVC to enter into the Merger Agreement
and to consummate the transactions contemplated thereby, the Executive agrees
to terminate the Executive Retention Agreement and the Offer Letter effective
immediately prior to the consummation of the merger contemplated by the
Merger Agreement;

         WHEREAS, in consideration for the Executive's termination of the
Executive Retention Agreement and the Offer Letter, the Company will grant to
the Executive options to purchase 150,000 shares of common stock, par value
$0.01, of the Company ("Company Common Stock") pursuant to the Company's 1996
Incentive and Nonqualified Stock Option Plan; and

         WHEREAS, the Executive has been granted and as of the date hereof
holds options to purchase Company Common Stock (the "Existing Options") which
are subject to certain vesting provisions as set forth in the option plans
and option agreements governing the terms of such Existing Options.

         NOW, THEREFORE, intending to be legally bound, the parties agree as
follows:

          1.   The parties agree that each of the Executive Retention Agreement
               and the Offer Letter shall terminate (without any liability or
               obligation to the parties thereof) and shall be of no further
               force or effect, effective as of immediately prior to the
               Effective Time (as defined in the Merger Agreement) and this
               Agreement (along with the exhibit attached hereto) shall govern
               Executive's relationship with the Company and FVC; PROVIDED
               HOWEVER, that in the event Executive's employment is terminated
               by FVC without Cause (as defined in the Agreement) within 12
               months after the date of the Effective Time, then Executive shall
               be entitled to the benefits afforded by Sections 4.1 (with
               respect solely to the Existing Options) and 4.2 of the Executive
               Retention Agreement, subject in all respects to the terms and
               conditions of such Sections 4.1 and 4.2.

          2.   The parties agree that, notwithstanding anything to the contrary
               contained in the Executive Retention Agreement or the Offer
               Letter, upon termination of each of the Executive Retention
               Agreement and the Offer Letter, the Company shall not have any
               payment or other obligations to the Executive, including, without
               limitation, payment obligations for severance, salary, bonus,
               employee benefits or similar payments.

<PAGE>

          3.   The parties agree that, notwithstanding anything to the contrary
               contained in the Executive Retention Agreement or the Offer
               Letter, upon termination of each of the Executive Retention
               Agreement and the Offer Letter, except as set forth in paragraph
               1 above, the vesting and exercisability of the Existing Options
               will not accelerate as a result of the Merger (as defined in the
               Merger Agreement) or the transactions contemplated thereby and
               will remain subject to their current vesting provisions as
               otherwise provided in the stock option plan of the Company under
               which such options were issued and in the stock option agreements
               by which such stock options are evidenced.

          4.   As partial consideration for Executive's agreement to terminate
               the Executive Retention Agreement and the Offer Letter, the
               Company shall, immediately prior to the Effective Time and
               simultaneously with the termination of the Executive Retention
               Agreement and the Offer Letter, grant to the Executive an option
               to purchase an aggregate of 150,000 shares of Company Common
               Stock pursuant to the Company's 1996 Incentive and Nonqualified
               Stock Option Plan or, if outside such plan, then on terms and
               conditions substantially similar to such plan. The exercise price
               of such option shall be equal to the fair market value of one
               share of Company Common Stock as quoted on The Nasdaq Stock
               Market on the date of execution of the Merger Agreement (or if
               such date is not a trading day, then the trading day immediately
               preceding the date of execution of the Merger Agreement).

          5.   As partial consideration for the Executive's agreement to
               terminate the Executive Retention Agreement and the Offer Letter,
               FVC shall enroll the Executive as a participant in FVC's
               Executive Officers Change of Control Plan (the "Change of Control
               Plan"), with such enrollment to become effective as of
               immediately after the Effective Time.

          6.   The Executive and FVC hereby agree to enter into the agreement
               attached hereto as Exhibit A at or prior to the Effective Time,
               with such agreement becoming effective as of immediately after
               the Effective Time.

                                       2.

<PAGE>

         Date:  March 22, 2001


                                       CUSEEME NETWORKS, INC.

                                       By: /s/ Killko Caballero
                                           ---------------------
                                       Name:
                                             -------------------
                                       Title:
                                              ------------------


                                       FIRST VIRTUAL COMMUNICATIONS, INC.

                                       By: /s/ Ralph Ungermann
                                           ---------------------
                                       Name: Ralph Ungermann
                                             -------------------
                                       Title:
                                              ------------------



                                       /s/ David Bundy
                                       -------------------------
                                       DAVID BUNDY

                                       3.

<PAGE>

                              [COMPANY LETTERHEAD]

April 11, 2001



David Bundy
142 Powder Hill Rd.
Bedford, NH 03110


RE:     ADDITIONAL EMPLOYMENT TERMS

Dear David:

This letter will clarify the terms of your employment with FIRST VIRTUAL
COMMUNICATIONS, Inc. (the "Company") as Chief Technology Officer, effective
as of the Effective Time, as defined in that certain Agreement and Plan of
Merger and Reorganization, dated as of March 22, 2001, between the Company,
CUseeMe Networks, Inc. and FVC Acquisition Corp., a wholly owned subsidiary
of the Company.

The Company may terminate your employment at any time and for any or no reason,
with or without Cause (as defined herein) or advance notice by giving written
notice of such termination. Similarly, you may terminate your employment with
the Company at any time at your election, in your sole discretion, for any or no
reason upon two (2) weeks notice to the Company during which time you shall
provide reasonable transition assistance to the Company. The Company reserves
the right to ask you to expedite your resignation date and to leave prior to the
end of the two-week notice period. The at-will nature of your employment
relationship may not be modified except by a written agreement between you and
the Chief Executive Officer of the Company.

Notwithstanding the above and subject also to paragraph 1 of the Agreement dated
March 22, 2001 between David Bundy, CUSeeMe Networks, Inc. and the Company (the
"Agreement"), if the Company terminates your employment without Cause, then upon
your furnishing to the Company an executed release and waiver of claims (a form
of which is attached hereto as EXHIBIT A), you shall be entitled to receive: (i)
severance payments in the form of continuation of your base salary in effect at
the time of your termination, subject to standard payroll deductions and
withholdings, for a period of six (6) months; (ii) bonus continuation payments
totaling your pro-rata share of the Target Bonus in effect on the date of
termination, paid on a monthly basis for six (6) months after the date of
termination; and (iii) your medical benefits paid for by the Company, assuming
that you are eligible for COBRA upon termination, until the earlier of either
(a) six (6) months after the date of termination, or (b) the date that you
become eligible to receive medical benefits with another company or business
entity. If your employment is terminated for Cause, or you voluntarily terminate
your employment from the Company, all compensation and benefits will cease
immediately and you will receive no additional payments from the Company other
than your accrued base salary and accrued and unused vacation benefits earned
through the date of your termination.

For purposes of this letter agreement, "Cause" shall mean (i) gross negligence
or willful misconduct by you, including, but not limited to, dishonesty which
materially and adversely reflects upon your ability to perform your duties for
the Company, (ii) your conviction of, or the entry of a pleading of guilty or
nolo contendere by you to, any crime involving moral turpitude or any felony,
(iii) fraud, embezzlement or theft against the Company, (iv) a material breach
by you of any material provision of any employment contract, assignment of
inventions, confidentiality and/or nondisclosure agreement between you and the
Company, or (v) your willful and habitual failure to attend to your duties as
assigned by the officer of the Company to whom you report if such
non-performance is not cured by you within thirty (30) days after you receive
written notice from the Company.

In the event that you are entitled to the benefits under the Company's Executive
Officer's Change of Control Plan, you will not be entitled to any of the
benefits or payments under this letter agreement.

This letter agreement (including Exhibit A attached hereto), the Agreement, the
Change of Control Plan and the Proprietary Information and Inventions Agreement
between you and the Company the complete and exclusive statement of the terms of
your employment with the Company and supersedes any other agreements or promises
made to you by anyone, whether oral or written.

Please sign and date this letter agreement, and return it to me on or before
April 11, 2001 if you wish to accept employment with the Company under the terms
described above.

We look forward to a productive and enjoyable work relationship.

Sincerely,


/s/ Ralph Ungermann
--------------------------------------
Ralph Ungermann
Chief Executive Officer and Chairman of the Board of Directors



Accepted:

/s/ David Bundy
--------------------------------------
David Bundy

April 11, 2001
--------------------------------------
Date

Attachment:    Exhibit A:    Waiver and Release


<PAGE>




                                    EXHIBIT A

                      FORM OF RELEASE AND WAIVER OF CLAIMS

        In consideration of the payments and other benefits set forth in the
Employment Agreement to which this form is attached, I, DAVID BUNDY, hereby
furnish FIRST VIRTUAL COMMUNICATIONS, INC. (the "Company"), with the following
release and waiver ("Release and Waiver").

        I hereby release, and forever discharge the Company, its officers,
directors, agents, employees, stockholders, successors, assigns affiliates and
Benefit Plans, of and from any and all claims, liabilities, demands, causes of
action, costs, expenses, attorneys' fees, damages, indemnities and obligations
of every kind and nature, in law, equity, or otherwise, known and unknown,
suspected and unsuspected, disclosed and undisclosed, arising at any time prior
to and including my employment Termination Date with respect to any claims
relating to my employment and the termination of my employment, including but
not limited to, claims pursuant to any federal, state or local law relating to
employment, including, but not limited to, discrimination claims, claims under
the California Fair Employment and Housing Act, and the Federal Age
Discrimination in Employment Act of 1967, as amended ("ADEA"), or claims for
wrongful termination, breach of the covenant of good faith, contract claims,
tort claims, and wage or benefit claims, including but not limited to, claims
for salary, bonuses, commissions, stock, stock options, vacation pay, fringe
benefits, severance pay or any form of compensation. The only claims excepted
from this Release are the following claims: a) any claims I may have for
benefits under the workers' compensation and unemployment insurance laws; b) my
legal right to continue medical coverage under COBRA; c) my right to vested
benefits under the Company `s 401(k) retirement plan; and d) my right to vested
stock in the Company.

        I also acknowledge that I have read and understand Section 1542 of the
California Civil Code which reads as follows: "A GENERAL RELEASE DOES NOT EXTEND
TO CLAIMS WHICH THE CREDITOR DOES NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT
THE TIME OF EXECUTING THE RELEASE, WHICH IF KNOWN BY HIM MUST HAVE MATERIALLY
AFFECTED HIS SETTLEMENT WITH THE DEBTOR." I hereby expressly waive and
relinquish all rights and benefits under that section and any law of any
jurisdiction of similar effect with respect to any claims I may have against the
Company.

        I acknowledge that, among other rights, I am waiving and releasing any
rights I may have under ADEA, that this Release and Waiver is knowing and
voluntary, and that the consideration given for this Release and Waiver is in
addition to anything of value to which I was already entitled as an executive of
the Company. I further acknowledge that I have been advised, as required by the
Older Workers Benefit Protection Act, that: (a) the Release and Waiver granted
herein does not relate to claims which may arise after this Release and Waiver
is executed; (b) I have the right to consult with an attorney prior to executing
this Release and Waiver (although I may choose voluntarily not to do so); and if
I am over 40 years of age upon execution of this Release and Waiver: (c) I have
twenty-one (21) days from the date of termination of my employment with the
Company in which to consider this Release and Waiver (although I may choose
voluntarily to execute this Release and Waiver earlier); (d) I have seven (7)
days following the execution of this Release and Waiver to revoke my consent to
this Release and Waiver; and (e) this Release and Waiver shall not be effective
until the seven (7) day revocation period has expired.

Date:                                         By:
------------------------------                   ------------------------------
                                                      DAVID BUNDY